Heater for fluids



Patented Oct. 10, 1944 HEATER FOR FLUIDS Marion W. Barnes, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a. corporation of Delaware Original application November 8, 1940, Serial No.

Divided and this application November 16, 1942, Serial No. 465,703

Claims. (01. 122-356) I This is a division of my co-pending application Serial No. 364,832, filed November 8, .1940, now Patent No. 2,324,553, July 20, 1943.

The invention is directed to, an improved form of heater which will be found particularly advantageous for heating fluid hydrocarbons to the high temperatures required for their conversion.

However, the invention is not restricted to this particular use, since it will find numerous other advantageous applications.

The heater herein provided is of the general type, now well known in the art, wherein flames and hot gases resulting from the combustion of fuel are passed upwardly or downwardly over the surface of spaced, substantially vertical refractory walls, heating the same to a highly radiant condition, heat being transmitted by radiation from the refractory walls and directly from the flames and hot gases to a fluid conduit disposed centrally between said walls. In the improved form of heater herein provided, said fluid conduit comprises three vertically parallel rows of horizontally disposed tubes, the tubes in adjacent rows being so arranged that the outer side of each of the tubes in the two outside rows receives heat directly by radiation from the adjacent reiractory wall and the flames and hot combustion gases passing thereover, while opposite sides of each of the tubes in the middle row receive heat by radiation from the flames, hot gases and the refractory walls at a reduced rate due to the partial shielding effect of the tubes in the two outer rows. With this arrangement, by varying the sequence of flow through the three rows of tubes and/or by varying firing conditions on opp sides of the fluid conduit, a wide variety of heating curves is obtainable and the desired flow may be selected to suit the requirements of the particular type of fluid undergoing treatment.

In the accompanying diagrammatic drawing Fig. 1 is an elevational view, shown principally in section, of one specific form of the heater provided by the invention.

Figs 2 and 3 of the drawing are flow diagrams representing two of the many specific manners in which the tubular fluid conduits of the threerow tube bank 8 of Fig. 1 may be interconnected.

Referring to Fig. 1, the single cell down-fired heater here illustrated has a foundation indicated at l on which a plurality of steel columns 2, supporting steel beams 3, are mounted. The steel framework supports the refractory shapes of sidewalls 4 and 5 and root 5 in any conventional manner not pertinent to theinvention and not here illustrated.

The substantially vertical portions of the side and end walls of the heater, which latter do not appear in this particular view, define combustion and radiant heating zones 1 and 8 which are disposed between the respective side walls 4 and 5 and fluid conduit 9. Th latter is located substantially midway between walls 4 and 5 and comprises three vertically parallel rows of horizontally disposed tubes ID with the adjacent tubes in the several rows arranged in staggered formation, as illustrated.

At their lower ends, theside walls 4 and 5 slope inwardly to connect with the side walls ii and i201? fluid heating zone i3 disposed beneath and in substantially vertical alignment with fluid conduit 9. Another fluid conduit l4 comprising,

4 in the case here illustrated, a plurality of superimposed horizontal rows of horizontally disposed tubes i5 is located within fluid heating zone 13.

A row of firing ports i6 is provided inthe roof of the furnace adjacent each of the side walls 4 and 5 and corresponding rows of burners l'l supply fuel and air to the combustion and heating zones 1 and 8 through firing ports 16. The burners and firing ports are so arranged that flames and hot gases resulting from combustion of the fuel are directed in a' substantially continuous sheet downwardly over the refractory surfaces of Walls 4 and 5, heating the latter to a highly radiant condition and keeping fluid conduit 9 out of the direct path of flow of the flames and hot combustion gases.

The tubes of fluid conduit 9 receive heat by direct radiation from the flames, hot combustion gases and radiant side walls of the heater. Since the tubes in the central row of bank 9 are par tially shielded by the tubes in the two outer rows, they are subjected to less intense heating than the tubes in the outer rows and, by varying the sequence of the fluid undergoing heating through the three rows of bank 9 and/or by varying the firing conditions employed on opposite sides of the heater, a wide variety of heating curves is obtainable and the type of heating curve obtained may be selected to suit the requirements 01' the particular type of fluid undergoing treatment.

The combustion gases, which have given up a major portion 01' their radiant heat to the tubular elements of bank 9, pass from the combustion and heating zones 1 and 8 through fluid heating zone l3 to flue l8 wherefrom they may pass to a suitable stack, not illustrated. The combustion gasesflowing through zon l3 intimately contact the tubes of bank l4 and supply heat to the latter and to the fluid passing therethrough.

Referring now to Fig. 2, this figure illustrates one manner in which the tubes of bank 9 and the several tube rows of this bank may be connected. In this particular case the fluid to be heated is divided into two streams of substantially equal volume which pass, respectively, in series through the tubes of the two outer rows in an upward direction. The two streams discharged from the uppermost tubes of the two outer rows are commingled and the commingled stream is passed downwardly in series through the tubes of the central row to be discharged from the lowermost tube thereof.

Referring now to Fig. 3, which is a view similar to that of Fig. 2' illustrating another specific flow through the heating coil, the flow here is substantially the reverse of that illustrated in Fig. 2. The fluid to be heated enters the uppermost tube of the central row, flowing downwardly in series through the tubes thereof and is divided as it leaves the lowermost tube of the central row I into two streams of substantially equal volume.

These two streams pass upwardly in series through the tubes of the two outer rows and are commingled following their discharge from the uppermost tubes of the two outer rows.

It will be apparent that many other specific flows are possible in the three-row tube bank 9. Several other flows are illustrated in my aforementioned co-pending application of which the present case is a division. The present application is directed particularly to. a flow through the heating coil in which a single stream of fluid is passed through the central row of the tube bank and separate streams of the same fluid are passed through the outer rows of the tube bank.

In Figs. 2 and 3, the general direction of flow through the various rows of tubes may be reversed. A clear picture of the reverse flows may be obtained by simply reversing the d rection of the arrows in each of these figures. Other possible variations will be apparent to one familiar with the art in view of the illustrations given. For example,' the general sequence of flow through the various rows may be preserved while employing either upward or downward flow in any individual row, as desired.

With heaters of the general type herein provided, the independent control of the quantity of fuei'supplied to the combustion and heatin zones permits maintaining substantially the same heating conditions in both of these zones or employing more severe or less severe conditions in one zone as compared with those employed in the other. Also, by varying the quantity of excess air supplied to each combustion and heating zone, the heating conditions may be varied from top to bottom of each zone.

Preferably, with the flows illustrated and above described, substantially equal heating conditions are employed in the two combustion zones on opposite sides of tube bank 9 and substantially equal quantities of fluid are passed through the two outer rows of this tube bank. Thus, the two paraillel streams of fluid passing through the two outer rows will be heated under substantially the same conditions.

My aforementioned co-pending application also illustrates and describes various modifications of the specific form of furnace structure shown in Fig. l of the present case. The features of the present invention may be employed in the other forms of furnace structures shown in the parent application, as well as in various additional modifications of the furnace structure, which will be apparent to those familiar with the art from the teachings of the invention.

I claim as my invention:

1. A heater for fluids comprising, in combination, refractory side and end walls defining a combustion and heating chamber, a tube bank comprising three vertically parallel rows of horizontal tubes disposed substantially midway between said side walls within said chamber, and means for directing flames and hot gases resulting from the combustion of fuel through said chamber over the inner surfaces of said refractory side walls in a substantially vertical direction and in radiant heat transmitting relation to said tube bank, said bank being constructed and arranged for the flow of a single stream of fluid through its central row of tubes and for the flow of separate streams of fluid from a common supply line through its outer rows.

2. A heater for fluids comprising, in combination, refractoryslde and end walls defining a combustion and heating chamber, a tube bank comprising three vertically parallel rows of connected with the adjacent lowermost tube of each of its outer rows.

3. A heater for fluids comprising, in combination, refractory side and end walls defining a combustion and heating chamber, a tube bank comprising three vertically parallel rows of horizontal tubes disposed substantially midway be-' tween said side walls within said chamber and means for directing flames and hot gases resulting from the combustion of fuel through said chambers over the inner surfaces'of said refractory side walls in a substantially vertical direction and in radiant heat transmitting relation to said tube bank, the adjacent tubes in each row of said bank being interconnected in series and the uppermost tube of its central row being connected with the adjacent uppermost tube of each of its outer rows.

4. A heater for fluids comprising a heating chamber having refractory side walls, a tube bank disposed within said chamber substantially midway between the side walls thereof, said bank comprising two vertically parallel outer rows of tubes and an intermediate row of tubes between said outer rows, means for passing hot combustion products through said chamber on opposite sides of the tube bank, means for passing a stream of fluid through one of said outer rows of tubes, means for passing a separate stream of fluid through the other outer row of tubes, and means for passing the fluid streams from both said outer rows through said intermediate row of tubes.

5. A heater for fluids comprising a heating chamber having refractory side walls, a tube bank disposed within said chamber substantially midway between the side walls thereof, said bank of tubes, means for passing a portion of the fluid stream from said intermediate row throughone of said outer rows of tubes, and means for passing another portion of the fluid stream from said intermediate row-through the other outer 5 row of tubes.

MARION W. BARNES. 

